FIG. 1 illustrates an example of a matrix display 100 comprising a number of light-emitting diodes 102. The diodes 102 are arranged in a number of columns and rows and each diode is connected between a column line 104 and a row line 106 associated with each column and row respectively. In particular, the cathodes of diodes 102 in a same row are connected to one of the row lines 106, and the anodes of diodes 102 in a same column are connected to one of the column lines 104.
Each column line 104 is connected to a respective current source 108, providing a determined current to the column line via a respective column switch 110. Column switches 110 selectively connect each column line to either the current source 108, or to a ground node, labelled GND in FIG. 1.
Each row line 106 is selectively connected to a rowoff voltage 112 via a respective row switch 114. Row switches 114 allow each row line 106 to be connected to one of the rowoff voltage or a ground node GND.
In operation, columns will be activated by switching column switches 110 such that selected current sources 108 are connected to respective column lines 104. Rows are successively selected by selectively connecting row lines 106 to the ground nodes using row switches 114. It is ensured that the diodes of unselected row lines remain switched off by connecting the cathodes of these diodes to the rowoff voltage 112 via their respective row line.
In the circuit of FIG. 1, the rowoff voltage is a fixed voltage, which is sufficiently high to ensure that the diodes of the row connected to this voltage are always off. A disadvantage of the circuit of FIG. 1 is that due to the necessarily high voltages applied to the cathodes of each of the diodes, the lifetime of these diodes is significantly reduced by high reverse biasing.